Bring back variable netmask code from revision 1.180, with some minor

changes; Print a warning when the DB slots are null, and return
standard 255.255.255.0. This is for the transition phase.
Also add version 12 modification to routerconfig; return the "src"
from the virt_routes table, so that the client side can figure out
what interface the route is associated with. There are associated
changes in libsetup to ifconfig,routerconfig,tunnelconfig.